THE SYNTHESIS OF 2'-DEOXY[7-15N]GUANOSINE HAS BEEN REPEATED FOR THIS FUNDING PERIOD BY MR. ASHBURN OF FURMAN UNIVERSITY. HE IS AN GRADUATE RESEARCH ASSISTANT WHO SPENT 6/93-7/94 WITH THE SIR RECEIVING TRAINING IN THIS SYNTHESIS. HE HAS TAKEN 2,4,6-TRIAMINOPYRIMIDINE AND REACTED THIS WITH THE N-15 DIAZONIUM SALT OF 4-BROMOANILINE TO GIVE THE AZO COMPOUND IN GOOD YIELD. CATALYTIC HYDROGENATION FOLLOWED BY ANNULATION WITH DIETHOXYMETHYLACETATE AFFORDED THE [7-15N]GUANINE. CONVERSION TO THE DEOXYNUCLEOSIDE WAS CARRIED OUT IN HIGH YIELD BY AN ENZYMATIC TRANSRIBOSYLATION REACTION USING THYMIDINE AS THE RIBOSYL DONOR. THYMIDINE PHOSPHORYLASE AND PURINE NUCLEOSIDE PHOSPHORYLASE WERE USED TO COUPLE THE RIBOSE TO THE PURINE BASE. THE YIELD WAS GREATER THAN 95%.